Note
New in version 0.4
Layers allow more flexible organization of test fixtures than test-, class- and module- level fixtures. Layers in nose2 are inspired by and aim to be compatible with the layers used by Zope’s testrunner.
Using layers, you can do things like:
A layer is a new-style class that implements at least a setUp classmethod:
class Layer(object):
@classmethod
def setUp(cls):
# ...
It may also implement tearDown, testSetUp and testTearDown, all as classmethods.
To assign a layer to a test case, set the test case’s layer property:
class Test(unittest.TestCase):
layer = Layer
Note that the layer class is assigned, not an instance of the layer. Typically layer classes are not instantiated.
Layers may subclass other layers:
class SubLayer(Layer):
@classmethod
def setUp(cls):
# ...
In this case, all tests that belong to the sub-layer also belong to the base layer. For example for this test case:
class SubTest(unittest.TestCase):
layer = SubLayer
The setUp methods from both SubLayer and Layer will run before any tests are run. The superclass’s setup will always run before the subclass’s setup. For teardown, the reverse: the subclass’s teardown runs before the superclass’s.
Warning
One important thing to note: layers that subclass other layers must not call their superclass’s setUp, tearDown, etc. – the test runner will take care of organizing tests so that the superclass’s methods are called in the right order:
Layer.setUp ->
SubLayer.setUp ->
Layer.testSetUp ->
SubLayer.testSetUp ->
TestCase.setUp
TestCase.run
TestCase.tearDown
SubLayer.testTearDown <-
Layer.testTearDown <-
SubLayer.tearDown <-
Layer.tearDown <-
If a sublayer calls it superclass’s methods directly, those methods will be called twice.
Not an actual class, but reference documentation for the methods layers can implement. There is no layer base class. Layers must be subclasses of object or other layers.
The layer’s setUp method is called before any tests belonging to that layer are executed. If no tests belong to the layer (or one of its sub-layers) then the setUp method will not be called.
The layer’s tearDown method is called after any tests belonging to the layer are executed, if the layer’s setUp method was called and did not raise an exception. It will not be called if the layer has no setUp method, or if that method did not run or did raise an exception.
The layer’s testSetUp method is called before each test belonging to the layer (and its sub-layers). If the method is defined to accept an argument, the test case instance is passed to the method. The method may also be defined to take no arguments.
The layer’s testTearDown method is called after each test belonging to the layer (and its sub-layers), if the layer also defines a setUpTest method and that method ran successfully (did not raise an exception) for this test case.
nose2 includes a DSL for setting up layer-using tests called “such”. Read all about it here: Such: a Functional-Test Friendly DSL.
The layers plugin module includes a second plugin that alters test report output to make the layer groupings more clear. When activated with the --layer-reporter command-line option (or via a config file), test output that normally looks like this:
test (test_layers.NoLayer) ... ok
test (test_layers.Outer) ... ok
test (test_layers.InnerD) ... ok
test (test_layers.InnerA) ... ok
test (test_layers.InnerA_1) ... ok
test (test_layers.InnerB_1) ... ok
test (test_layers.InnerC) ... ok
test2 (test_layers.InnerC) ... ok
----------------------------------------------------------------------
Ran 8 tests in 0.001s
OK
Will instead look like this:
test (test_layers.NoLayer) ... ok
Base
test (test_layers.Outer) ... ok
LayerD
test (test_layers.InnerD) ... ok
LayerA
test (test_layers.InnerA) ... ok
LayerB
LayerC
test (test_layers.InnerC) ... ok
test2 (test_layers.InnerC) ... ok
LayerB_1
test (test_layers.InnerB_1) ... ok
LayerA_1
test (test_layers.InnerA_1) ... ok
----------------------------------------------------------------------
Ran 8 tests in 0.002s
OK
The layer reporter plugin can also optionally colorize the keywords (‘A’, ‘having’, and ‘should’ by default) in output from tests defined with the such DSL.
If you would like to change how the layer is displayed you need to set the description attribute.
class LayerD(Layer):
description = '*** This is a very important custom layer description ***'
Now the output will be the following:
test (test_layers.NoLayer) ... ok
Base
test (test_layers.Outer) ... ok
*** This is a very important custom layer description ***
test (test_layers.InnerD) ... ok
LayerA
test (test_layers.InnerA) ... ok
LayerB
LayerC
test (test_layers.InnerC) ... ok
test2 (test_layers.InnerC) ... ok
LayerB_1
test (test_layers.InnerB_1) ... ok
LayerA_1
test (test_layers.InnerA_1) ... ok
----------------------------------------------------------------------
Ran 8 tests in 0.002s
OK
Test cases that use layers will not execute in the same order as test cases that do not. In order to execute the layers efficiently, the test runner must reorganize all tests in the loaded test suite to group those having like layers together (and sub-layers under their parents). If you share layers across modules this may result in tests from one module executing interleaved with tests from a different module.
Don’t cross the streams.
The implementation of class- and module-level fixtures in unittest2 depends on introspecting the class hierarchy inside of the unittest.TestSuite. Since the suites that the layers plugin uses to organize tests derive from unittest.BaseTestSuite not unittest.TestSuite, class- and module- level fixtures in TestCase classes that use layers will be ignored.
In the initial release, test suites using layers are incompatible with the multiprocess plugin. This should be fixed in a future release.
Default : | False |
---|---|
Type : | boolean |
Default : | False |
---|---|
Type : | boolean |
Default : | [‘A’, ‘having’, ‘should’] |
---|---|
Type : | list |
Default : | |
---|---|
Type : | str |
The default configuration is equivalent to including the following in a unittest.cfg file.
[layer-reporter]
always-on = False
colors = False
highlight-words = A
having
should
indent =